///*
//* Created by boil on 2023/11/22.
//*/
//
//#include "debug_log.h"
//#include <chrono>
//#include <coroutine>
//#include <exception>
//#include <future>
//#include <iostream>
//#include <thread>
//#include <type_traits>
//
//// A program-defined type on which the coroutine_traits specializations below depend
//struct as_coroutine {};
//
//// Enable the use of std::future<T> as a coroutine type by using a std::promise<T> as the promise type.
//template<typename T, typename... Args>
//  requires(!std::is_void_v<T> && !std::is_reference_v<T>)
//struct std::coroutine_traits<std::future<T>, as_coroutine, Args...> {
//  struct promise_type : std::promise<T> {
//    std::future<T> get_return_object() noexcept {
//      return this->get_future();
//    }
//
//    std::suspend_never initial_suspend() const noexcept { return {}; }
//    std::suspend_never final_suspend() const noexcept { return {}; }
//
//    void return_value(const T &value) noexcept(std::is_nothrow_copy_constructible_v<T>) {
//      this->set_value(value);
//    }
//
//    void return_value(T &&value) noexcept(std::is_nothrow_move_constructible_v<T>) {
//      this->set_value(std::move(value));
//    }
//
//    void unhandled_exception() noexcept {
//      this->set_exception(std::current_exception());
//    }
//  };
//};
//
//// Same for std::future<void>.
//template<typename... Args>
//struct std::coroutine_traits<std::future<void>, as_coroutine, Args...> {
//  struct promise_type : std::promise<void> {
//    std::future<void> get_return_object() noexcept {
//      return this->get_future();
//    }
//
//    std::suspend_never initial_suspend() const noexcept { return {}; }
//    std::suspend_never final_suspend() const noexcept { return {}; }
//
//    void return_void() noexcept {
//      this->set_value();
//    }
//
//    void unhandled_exception() noexcept {
//      this->set_exception(std::current_exception());
//    }
//  };
//};
//
//// Allow co_await'ing std::future<T> and std::future<void> by naively spawning a new thread for each co_await.
//template<typename T>
//auto operator co_await(std::future<T> future) noexcept
//  requires(!std::is_reference_v<T>)
//{
//  struct awaiter : std::future<T> {
//    bool await_ready() const noexcept {
//      using namespace std::chrono_literals;
//      return this->wait_for(0s) != std::future_status::timeout;
//    }
//
//    void await_suspend(std::coroutine_handle<> cont) const {
//      std::thread([this, cont] {
//        this->wait();
//        cont();
//      }).detach();
//    }
//
//    T await_resume() { return this->get(); }
//  };
//
//  return awaiter{std::move(future)};
//}
//
//// Utilize the infrastructure we have established.
//std::future<int> compute(as_coroutine) {
//  int a = co_await std::async([] {
//    using namespace std::chrono_literals;
//    std::this_thread::sleep_for(4s);
//    return 6;
//  });
//
//  int b = co_await std::async([] {
//    using namespace std::chrono_literals;
//    std::this_thread::sleep_for(3s);
//    return 7;
//  });
//
//  co_return a *b;
//}
//
//std::future<void> fail(as_coroutine) {
//  throw std::runtime_error("bleah");
//  co_return;
//}
//
//int future_test() {
//  std::cout << compute({}).get() << '\n';
//
//  try {
//    fail({}).get();
//  } catch (const std::runtime_error &e) {
//    std::cout << "error: " << e.what() << '\n';
//  }
//}
